Download Nerve Ending

Nervous tissue
神经组织
Jun Zhou(周俊)
School of Medicine, Zhejiang University
20140325
Overview
---Components:
 nerve cell: neuron
 Glial cell: neuroglia
---Function:
 Neurons : receive the stimulation, conduct the
nerve impulse
 Glial cell: support, protect and insulate,
nourish neurons
Synapse
•neuron
Nerve fiber
neuroglial
ending
neuron
Neuron
The structural and functional cellular unit
LM:
---cell body: spherical,
pyramidal fusiform or
stellate in shape, 5um150um
---dendrite （树突）
---axon （轴突）
structure of neuron
① cell body:
---cell membrane:

unit membrane-irritability, receive stimuli, initiate
and conduct nerve impulse

membrane proteins - ions channel and receptor
cell nucleus:
 large and round
 centrally- located
 less heterochromatin
 pale stained, with a clear nucleolus
---cytoplasm: perikaryon
a. Nissl body (尼氏体):
LM: basophilic granule-liked structure
EM: parallelly-arranged RER and free ribosome
Function: synthesis proteins
 structural protein
 enzymes of neurotransmitters
b. Neurofibril(神经原纤维):

silver impregnation
(silver preparation)
methods

thread-liked dark brown color
structure to form a network.
EM:


neurofilament: 10 nm in diameter
microtubule: 25 nm in diameter
Function:


supporting
involving in intracellular transportation
c. other organelle
 Golgi apparatus
 mitochondria
 pigment
②




dendrite(树突):
many, short and more branches
structure similar to cell body
dendritic spine (synapse) and spine apparatus
(structure formed by 2-3 layers SER)
Function: receive the information
③
axon(轴突):
thin, less branch
 axon hillock(轴丘): the beginning without Nissl body
 axolemma
 axoplasm
---Function: initiate an impulse and conduct the impulse

* axonal transports
 slow anterograde
cytoskeletal
protein:
microtubule,
microfilament and neurofilament (0.10.4 mm/d)

fast anterograde
synaptic vesicles, enzymes and
proteins( 100-400 mm/d)

fast retrograde
products of metabolism, intaking
materials
including
protein
or
neurotropic factors (100-300 mm/d)
3) classification:
---According to the number of
processes



multipolar neuron
bipolar neuron
pseudounipolar neuron
---According to length of axon
 Golgi type I neuron
long axon and large
 Golgi type II neuron
short axon
---According to function
 sensory neuron
 motor neuron
 interneuron
---According to the neurotransmitter or
neuromodulator




cholinergic neuron
aminergic neuron
peptidergic neuron
aminoacidergic neuron
Synapse (突触)
---definition: the junctions between
neurons or neuron and non-nerve cells
---classification:
 chemical synapse: taking
neurotransmitter as communicating
medium
 electrical synapse: gap junction
---structure of chemical synapse:
LM
 in silver preparation
 on the surface of dendrites and cell body
 button-liked structures (synaptic button)
EM
1)presynaptic element: axonal terminal


presynaptic membrane
synapse vesicle:
-round or flattened, 40-60nm
-clear or with electron dense core
2)synaptic space: 15-30nm
3)postsynaptic element:


postsynaptic membrane
receptors
Glial cell (neuroglia)
神经胶质细胞
Glial cell in CNS






Astrocyte (星形胶质细胞)
fibrous astrocyte
protoplasmic astrocyte
Oligodendrocyte (少突胶质细胞)
Microglia (小胶质细胞)
Ependymal cell (室管膜细胞)
fibrous astrocytes
-white matter, have long, thin and smooth processes
-more glial filament- glial fibrillary acidic protein, GFAP
protoplasmic astrocytes
-gray matter, short, thick processes with more branch
-less glial filament

Oligodendrocyte(少突胶质细胞):
 smaller, fewer process
 form myelin-sheath of NF in CNS
Microglia(小胶质细胞):


smallest, elongate shape
or ovoid, with a small dark
irregular N
phagocytosismononuclear
phagocyte
system？
Ependymal cell (室管膜细胞):



simple cuboidal or columnar epi
apical: microvilli and cilia
basal: long processes
---Distribution: ventricle of brain and central canal of
spinal cord
Glial cell in PNS
a. Schwann cell:
form myelin-sheath in PNS
b. Satellite cell (capsular cell):
surrounding the Neuron in ganglion
Nerve fiber and Nerve
 formed by axon and glial cell
 classification
 myelinated nerve fiber (有髓神经纤维)
 unmyelinated nerve fiber (无髓神经纤维)
Myelinated nerve fiber
LM:








Axon
myelin-sheath:
net-liked
OsO4(osmium tetroxide) fixation and stain
Schmidt-Lantermann incisure
neurilemma: cell membrane +basement membrane
Schwann cells (PNS)
Oligodendrocyte (CNS)
Ranvier
node (郎飞结): narrow part, no myelinsheath- saltatory conduction
Internode segment (结间体): the segment of NF
between two Ranvier nodes
MNF in CNS




similar to that of PNS
oligodendrocyte
one oligodendrocyte can envelop many axons
no incisure and basement membrane
Unmyelinated nerve fiber
thin
axon and Schwann cell connect end to end
no myelin-sheath and Ranvier node
one Schwann cell envelops more axons
naked axon (CNS)
Nerve
---Nerve fiber gets together



Epineurium
perineurium
endoneurium
Blood brain barrier (血脑屏障)



Endothelial cell of continuous Cap.
basement membrane
Foot processes of astrocytes
Nerve Ending
Sensory nerve ending
1.Free nerve ending
---function: feel cold, hot, pain and slight touch
2.Encapsulated N ending
---have CT capsule



Meissner’s corpuscle (tactile)触觉小体: touch receptor
Pacinian corpuscle(lamellar)环层小体: pressure receptor
Muscle spindle(肌梭): tension receptor
tactile corpuscle
lamellar corpuscle
Muscular
spindles
Motor nerve ending
Somatic
MNE: motor end plate ( neuromuscular
junction)
Visceral MNE
THE END